The overall objective of this project is to study the conditions favoring the licalization of CEA-containing human tumors in animal systems by means of radiolabeled anti-CEA antibody preparations and total-body photoscanning. A study of these conditions involves investigations of (a) the antibldy preparation, (b) radionuclide labeling, and (c) the appropriate tumor model containing the antigen in question. Of basic question is the immunopharmacokinetics of the xenogenic radioantibody preparation in the tumor-bearing host. Our experiments in this project are to be carried out concurrently with clinical trials of our original anti-CEA IgG preparation, and will represent the experimental basis for future clinical studies of other radioantibody products.